Hermetically sealed containers with unitary closures are known in the art. Generally, such containers are made using apparatus and methods for forming, filling, and sealing as disclosed generally in the U.S. Pat. No. Re. 27,155 and in the U.S. Pat. No. 3,597,793. Typically, such containers are of unitary construction and may be provided with a closure that can be severed to permit removal of the closure and to permit access to the contents in the container. Containers of this general type are well suited for sterile and aseptic packaging of various liquids.
A number of designs for such unitary containers have been proposed wherein the closure can be severed from the container by rotating a ring in threaded engagement with the container. Such containers typically include a neck portion with an external thread, a cover portion closing the neck portion, and a frangible web joining the cover portion to the neck portion. A ring is provided with an internal thread for engaging the external thread on the container neck portion. As the ring is rotated in one direction on the neck portion, part of the ring engages the cover portion and forces it in an axial direction relative to the container neck portion so as to sever the frangible web.
Of interest in this regard are the designs disclosed in the U.S. Pat. Nos. 4,176,755 and 4,207,990. U.S. Pat. No. 4,176,755 discloses a container with an outer ring having external protuberances which engage an outwardly extending bearing surface of the container closure or cover portion. When the ring is screwed downwardly with respect to the container neck portion, a portion of the ring forces the container cover portion downwardly to fracture the frangible web and separate the cover portion from the container neck portion. Next, to permit access to the container contents and to permit the contents to be discharged from the container, the ring is screwed upwardly relative to the container neck portion. This causes the top of each protuberance to engage a retaining abutment on the now severed cover portion so as to lift the separated cover portion as the outer ring is unscrewed from the container.
U.S. Pat. No. 4,207,990 discloses a container with a collar or ring having a plurality of blades engaged with the underside of an annular flange projecting outwardly above the severable web joining the container cover portion to the container neck portion. When opening the container, the ring is rotated in the direction to unscrew it from the container neck portion. This forces the blades to abut the underside of the flange. Upon further elevation of the ring as it is rotated, the blades are deflected inwardly so as to incise the frangible web while at the same time exerting an upward lifting force on the flange. Continued elevation of the ring results in complete removal of the cover portion from the neck portion of the container, thereby exposing an access opening to the container.
Although the above-discussed containers may be satisfactorily opened by proper operation of the opening rings, it would be desirable to provide an improved design having advantages not found in such current designs. Specifically, in those situations where sterility, dust, or dirt accummulation may be a problem, it would be desirable to provide means for eliminating, or at least minimizing, the possibility that contaminants may be deposited at or near the container cover portion.
By the same token, it would be desirable to eliminate or reduce access to the frangible web area of the container so as to eliminate, or substantially reduce, the likelihood of contamination of the frangible web area. In this respect, it is to be noted that in each of the above-discussed current designs, the opening ring elements instrumental in severing the cover portion are exposed to the ambient atmosphere and to the contaminants therein. Further, the frangible web region is also exposed to the ambient atmosphere in the design disclosed in U.S. Pat. No. 4,207,990.
The frangible web region in the design shown in U.S. Pat. No. 4,176,755 can also be exposed to the ambient atmosphere if the opening ring is threaded upwardly a slight amount providing space between the container cover portion and the opening ring at the base of the protuberances even though it may not be apparent to the casual observer that such a contaminant flow path exists. Indeed, if this situation were not noted and corrected, the region between the opening ring and the frangible web could retain contaminant material. Then, when the container cover portion is opened by rotating the ring further to actually fracture the frangible web, the accumulated contaminants could enter the contents of the container as the cover portion is removed from the container. Accordingly, it would be desirable to provide a design in which the container frangible web region is protected and not susceptible to such potential contamination.
Finally, it would be beneficial to provide an efficient means for effecting the severing of the cover portion from the container neck portion in a manner that would not require an undue amount of applied torque. In this respect, it is to be noted that each of the extraneous members of the opening ring in each of the above-discussed current designs are arcuate for engaging the circumferential surface of the container cover portion. Thus, when the opening ring is rotated to effect the severing of the frangible web, the leading edge of each member may dig into the adjacent wall of the cover portion. This, at a minimum, will create a greater frictional force and, in any event, will require increased torque to continue the rotation of the opening ring so as to provide sufficient axial thrust to fracture the frangible web. Accordingly, it would be desirable to provide an improved structure for opening such a container with a reduced torque requirement.